Automatic variable pitch propeller



May 12, 1953 F c, Foss 2,638,171

' AUTOMATIC VARIABLE PITCH PROPELLER Filed Sept. 50, 1947 2 sheets-sheet1 Fig. 7.

Inventor F [9. 6. Freeman 0. Fuss y 12, 1953 F. c. Foss 2,638,171

AUTOMATIC VARIABLE PITQI-I PROPELLER Filed Sept. :50, 1947 2Sheets-Sheet 2 36 I W /V Inventor Freeman 0. Foss Attorneys Patented May12, 1953 "1Z5 UNITED STATES PATENT OFFICE AUTOMATIC VARIABLE PITCHPROPELLER Freeman 0. Foss, Twin Falls, Idaho Application September 30,1947, Serial No. 777,004

This inventionappertains to novel and useful improvements in propellersof the automatic cOntrollable pitch type.

An object of this invention is to provide an improved blade constructionwhich, by selectively shaping certain portions thereof, the blade 18urged to selected controlled pitch positions while being acted on by afluid medium.

Another object of this invention is to provide means for retainingpropeller blades in the reversed flow position.

Another object of this invention is toprovide means for adjustablycontrolling the travel of the blades.

A further object of this invention is to provide means for controllingthe pitch of the propeller blades in order that the usual power plantassociated therewith may be operated at the most efficient horsepoweroutput.

Another purpose of this invention is to provide a relatively simpledevice capable of performing all of the above mentioned objects which iscommercially feasible, practical and smoothly operative.

Other objects and features of novelty will be come apparent to thoseskilled in the art, in following the description of the preferredembodiment of the present invention, illustrated in the accompanyingdrawings, wherein:

Figure l is an elevational view of the present invention;

Figure 2 is a fragmentary front view of the invention disclosed inFigure 1 and taken substantially on the line 2-2 thereof and in thedirection of the arrows;

Figure 3 is a longitudinal sectional view of the actuating means withthe propeller blades removed, taken substantially on the line 3-3 ofFigure 2 and in the direction of the arrows;

Figure 4 is a side view of theinvention disclosed in Figure 1, theblades being in a reversed position and portions being broken away insection to illustrate details of construction;

Figure 5 is a perspective view of the cam means forming part of theinvention and the offset shaft for pivoting the blades;

Figure 6 is a reduced plan view of the body member forming part of theinvention, portions being broken away to illustrate details ofconstruction;

Figures 7, 8 and 9 are sectional views of the blade construction takenon the respective lines of Figure 1.

The device illustrated by the present invention may be utilized withsubstantially all outboard 1 Claim. (Cl. 170-160.51)

and inboard motors as either an accessory or, if desired, a stock part.The general operation of the invention is relatively simple and will beset forth at this time, since this will lead to a better understandingof the mechanical elements to be set forth hereinafter.

A plurality of blades ID are provided which, due to a particular flareback on the trailing edge, the pitch of the blades vary whenever themotor speed is changed. Each of the blades utilized in the presentinvention is pivoted at substantially the center of pressure or in aplane parallel or substantially parallel thereto. Of course, it is wellknown that the center of pressure varies under certain conditions.However, it is also realized that the said center of pressure varies onlwithin certain limits and it is within these limits that the pivot forthe blades is secured. Due to the water pressure increasing on theblades as the same increases in torque and decreasing when the motor isdecelerated or torque is lessened, the blades always seek apredetermined value of pitch angle, commensurate with the most efficientoperation of the associated power means.

There is provided cam means for actuating certain elements to bedescribed later, and this cam means is provided with a flat part wherebythe blades may even be held in a position to effect traction in areverse direction. Under these conditions the pivot point of each bladeis in a dead center relation with regard to an edge ofthe cam and theurging force of either the spring or the hydraulic means.

Taking, now, a feature of the present invention, the blades will bedescribed in detail. The leading edge of each blade is provided with aslight sweep back l2. The trailing edge of each blade is provided with aforwardly flared portion I4. The last-mentioned flared portion forms'amaterial part of the present invention, since it is this forwardlyflared portion which, when utilized in conjunction with the pivotlocation, urges the blades automatically to the proper pitch position. Acam I6 is secured to the base of each blade and the cam has a flat partor seat l8.

A shaft 20 is secured to each cam l 6 and is substantially at the centerof pressure of the blade as a whole. It will be noted that the saidshaft 20 is supplied with threads at the terminal portion thereof.

A body member or housing 22 is provided for use in conjunction with thepresent invention. For this construction, reference is made to Figure 3wherein there is disclosed the body member 22 having a sleeve 24slidably disposed thereover. Bearings 26 with apertures 21 are securedto, or formed integral with the body member 22 adjacent one end thereoffor the purpose of supporting the shaft 20 of the respective blades. Theflat cams l6 engage a complemental cam surface I! on the forward portionof the said sleeve 24 and, as the blades are rotated about the pivot pin20, the sleeve 24 is urged axially of the housing or body member 22,against the biasing action of a spring 28.

The spring 28 is disposed between the sleeve 24 and the housing 22. Theterminal portion of the said housing 22 is externally threaded and a nut30 applied thereto in order to retain the said spring 28 Within thesleeve 24. Suitable packing means 32, conventional in nature, may besupplied as well as any number of Washers and the like, which may befound advantageous- It will be noted that a plurality of apertures 34provided in the body member 22 for the purpose of preventing vacuum lockbetween the member 22 and sleeve A power shaft 3t extends through thesaid housing 22 and a shear pin 31?, extendsv therethrough and throughsaid power shaft. The terminal. portion of the shaft 3% is received in asecond. housing 49, positioned within a bore in the said. housing 22.This second housing 40 is threadedly received on the terminal portion ofthe said power shaft St. A limiting bolt 42 is provided, in the saidsecond housing id and en-- gages-the said power shaft Means. forlimiting the pivotal travel of the blades is. provided. This meansconsists of a pair of set screws 44 and respectively, which areadj-ustabiy secured in holes in an outer 41- of said: housing These setscrews engage a selected portion of the said cams it, as is quiteapparent. from an inspection of Figure 1.

As is' seen in Figure 1, the shaft 25 extends through the bore 275 orthe bearing 26 and a. suitable castle n-ut or the like 48 is applied tothe threaded. portion thereof. of course, a cotter pin 50, or the like,may be utilized in conjunction therewith for the. usual function ofretaining the castle nut. in the desired, tight position.

It is noted that most outboard motors or even inboard motors utilize theconventional gasoline or oil asfuel. Accordingly, in marine engines ofthis nature, fouling and insufiicient operation may be effected if theengine operated very slowly for a. long time. With theuse oi the presentinvention, the engine may run or operate at a. higher value of R- F.and. supply the same horsepower output or value of torque- Obviously,this permits higher eiiiciency of engine operation.

A portion of this reserved, slower speed of. engine operation can beused to reverse the direction of. the water displacement by the blades.At difierent values. of torque, the blades, due to the flare back of thetrailing edge and due to the advantageous. position of the pivot on, orsubstantially onv the center of pressure, assume varied angles of.pitch- At very slow speed, the pitch angle approaches a reversedirection and even upon slower speed, the blades actually do reverseflow of displacement- Since the fiat part it of the cam I6 is then.disposed on the cam surface 4 H, the blades will be retained in thisreverse direction until a burst of speed pulls them out of this reversedirection. The cams it may be designed in such a way that slightincrease in speed may be efiected without pulling the blades from theirreverse position in order to obtain a backward motion of the entire boaton which the invention is applied. Of course, since the blades are inthe very slightly reversing direction or flow-producing direction,starting of the engine will be materially reduced in difficulty due tothe almost absence of torque required to propel the blades in thisposition.

Having described the invention, what is claimed as new is:

In a controllable pitch propeller, a body member of longitudinal formand having a longitudinal axis, a sleeve concentrically located on theexterior of a part of said body member and slidable axially of said bodymember, means operatively' connected with said sleeve and said bodymember yieldinglyrestricting relative axial move.- ment of said sleeveand said body member, a bearing at one end. of said: body member, saidbearing having openings therein each of which has a longitudinal. axisperpendicular to said b dy member axis, blades, pivot pins securedv tothe root ends of said blades and. disposed in said openings therebyrotatatively' mounting, said blades about axes of rotation normal tosaid longitudinal axis of said body member, cams fixed to the root endsof said blades and each cam havingv a land, oomplemental cam, means onsaid sleeve contacted by said cams so that when said blades are rotated.a predetermined amount to move the sleeve away from said 0116:61Idofsaid body member, said lands rest upon: said cam means to" retain. saidblades? rotated, adjustable means on said body member and: in the path.of rotation. of: said cams for limiting the. rotation; of said blades assleeveis. moved toward the said one end of said body member, and meanscomprising curved. trailingedges. of each of Said blades for rotativelyurging said blades to varied positions of blade. pitch. angie.

FREEMAN C. FOSS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 136,015 Wilson Feb. 18, v 187 711,021 Thaxter -1 Oct. 14, 190

1,386,490. Boerner r Aug..2,, 1921 1,555,422 Lorenzen Sept" 29-, 19251,887,543 Chilton NOV. 15-, 1932 1,978,788 Furgason Oct. 39,19341,987,651 Wiegand Jan. 15, 1935 2,005,3sl3. Kent. .--1 1 June 18, 19352,997,663. Raggio- Now-2, 1937 2,099,922. Bellman Nov. 23,. 1-9372,299,666. Ashelrnan et all. July 21, 1942 2,422,138. Seewer June 1.0,1947? 2,595,434. Troller' Jan. 24, 1950 2,498,109 Lathrem Feb. 2, 1950FOREIGN PATENTS Number Country Date 7,084 Great Britain of. 1909 10,098

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